No Arabic abstract
We propose a fast and robust quantum state transfer protocol employing a Su-Schrieffer-Heeger chain, where the interchain couplings vary in time. Based on simple considerations around the terms involved in the definition of the adiabatic invariant, we construct an exponential time-driving function that successfully takes advantage of resonant effects to speed up the transfer process. Using optimal control theory, we confirm that the proposed time-driving function is close to optimal. To unravel the crucial aspects of our construction, we proceed to a comparison with two other protocols. One where the underlying Su-Schrieffer-Heeger chain is adiabatically time-driven and another where the underlying chain is topologically trivial and resonant effects are at work. By numerically investigating the resilience of each protocol to static noise, we highlight the robustness of the exponential driving.
Robust quantum state transfer (QST) is an indispensable ingredient in scalable quantum information processing. Here we present an experimentally feasible mechanism for realizing robust QST via topologically protected edge states in superconducting qubit chains. Using superconducting Xmon qubits with tunable couplings, we construct generalized Su-Schrieffer-Heeger models and analytically derive the wave functions of topological edge states. We find that such edge states can be employed as a quantum channel to realize robust QST between remote qubits. With a numerical simulation, we show that both single-qubit states and two-qubit entangled states can be robustly transferred in the presence of sizable imperfections in the qubit couplings. The transfer fidelity demonstrates a wide plateau at the value of unity in the imperfection magnitude. This approach is general and can be implemented in a variety of quantum computing platforms.
We investigate the quantum state transfer in a chain of particles satisfying q-deformed oscillators algebra. This general algebraic setting includes the spin chain and the bosonic chain as limiting cases. We study conditions for perfect state transfer depending on the number of sites and excitations on the chain. They are formulated by means of irreducible representations of a quantum algebra realized through Jordan-Schwinger maps. Playing with deformation parameters, we can study the effects of nonlinear perturbations or interpolate between the spin and bosonic chain.
We show that it is possible to successfully, rapidly and robustly transfer a topological vibrational edge mode across a time-varying mechanical chain. The stiffness values of the springs of the chain are arranged in an alternating staggered way, such that we obtain a mechanical analog of the quantum Su-Schrieffer-Heeger model which exhibits a non trivial topological phase. Using optimal control methods, we are able to design control schemes for driving the stiffness parameters, such that the transfer is done with high fidelity, speed and robustness against disorder as well as energy amplification of the target edge mode.
Transferring quantum information between two qubits is a basic requirement for many applications in quantum communication and quantum information processing. In the iterative quantum state transfer (IQST) proposed by D. Burgarth et al. [Phys. Rev. A 75, 062327 (2007)], this is achieved by a static spin chain and a sequence of gate operations applied only to the receiving end of the chain. The only requirement on the spin chain is that it transfers a finite part of the input amplitude to the end of the chain, where the gate operations accumulate the information. For an appropriate sequence of evolutions and gate operations, the fidelity of the transfer can asymptotically approach unity. We demonstrate the principle of operation of this transfer scheme by implementing it in a nuclear magnetic resonance quantum information processor.
The transfer of quantum states has played an important role in quantum information processing. In fact, transfer of quantum states from point $A$ to $B$ with unit fidelity is very important for us and we focus on this case. In recent years, in represented works, they designed Hamiltonian in a way that a mirror symmetry creates with with respect to network center. In this paper, we stratify the spin network with respect to an arbitrary vertex of the spin network o then we design coupling coefficient in a way to create a mirror symmetry in Hamiltonian with respect to center. By using this Hamiltonian and represented approach, initial state that have been encoded on the first vertex in suitable time and with unit fidelity from its antipodes vertex can be received. In his work, there is no need to external control.